The document describes the construction of a 5-level basement for an international financial center building in Hong Kong. A 71-meter diameter cofferdam was constructed down to a depth of -35 meters to form the raft foundation for the main tower. The basement levels were constructed using a top-down approach, where the ground floor was excavated and subsequent levels were constructed below through repeated vertical and horizontal excavation and construction of diaphragm walls and structural elements like columns. Spoil removal utilized a material hoist and muck openings in the basement floors. The basement was constructed in a "double bit" manner to efficiently carry out excavation and construction.

1. INTERNATIONAL
FINANCIAL
CENTRE, HONG KONG
BUILDING CONSTRUCTION- DEEP BASEMENT

2. INTRODUCTION
SITE AREA: ABOUT 20000 SQ M
GENERAL CHARACTERISTICS
• LIKE TYPICAL HONG KONG THE SITE HAS DEPOSITION OF GRADE III
GRANITE AND ALUVIUM AT THE HEIGHT OF -35 M
• SILL AT THE HEIGHT OF -20M
• 5-LEVEL BASEMENT CONSTRUCTED USING TOP-DOWN
ARRANGEMENT
• BASEMENT WORKS INVOLVED
- PORTION UNDER THE MAIN TOWER
- PORTIUM UNDER THE RETAIL PODIUM
• A 71M DIAMETER COFFERDAM DOWN TO – 35M WAS CONSTRUCTED TO
• FORM THE RAFT FOUNDATION FOR THE BUILDING CORE OF THE MAIN TOWER
• PORTION UNDER THE RETAIL PODIUM WAS CONSTRUCTED USING TOP-DOWN
APPROACH

3. PROCESS
• INITIALLY THE 71M DIA COFFERDAM AND THE MEGA COLUMNS ALONG WITH THE CORE WALL WERE
CONSTRUCTED.
• THEN THE CAR RAMP ON THE LEFT
• FOLLOWING THE TOP DOWN METHOD THE GROUND FLOOR IS CREATED BY EXCAVATION AND THEN ALSO A PIT
CALLED DOUBLE BIT HELPS IN CARRYING THE SPOILS FROM THE EXCAVATION
• THEN THE DIAPHRAGM WALLS ON THE SUBSEQUENT SIDES ARE BROUGHT DOWN TO ALLOW ENTRY
• THE SAME PROCESS IS REPEATED VERTICALLY AND HORIZONTALLY TO CREATE LEVELS BELOW
• WHEN NEEDED THE EXPOSED STRUCTURAL ELEMENTS LIKE COLUMNS ARE THEN PRECASTED FOR FURTHER
PROTECTION AND STRENGTHENING

4. THE USE OF A MATERIAL HOIST FOR THE REMOVAL OF
SPOIL FROM THE BASEMENT INTERIOR

5. MUCK OPENING PROVIDED ON THE
GROUND SLAB FOR THE REMOVAL OF SPOIL
EXCAVATION INSIDE THE BASEMENT
CONSTRUCT THE BASEMENT IN A “DOUBLE BIT” MANNER

6. FORMING THE BASEMENT SLAB AND ENCASING THE STANCHION TO
FORM THE COLUMN

7. THANK YOU
RIZVI COLLEGE OF ARCHITECTURE
HATIM MERCHANT 1232
SHAHKHIZER SHAMSI 1367
AHMED BATLIWALA 1306